Package for high pressure treatment and method for treating foods at high pressure

ABSTRACT

A package for high pressure treatment of foods and a method for treating foods at a high pressure, both being able to easily determine whether the foods accommodated in the package have been subjected to a high pressure treatment or not. The package for high pressure treatment includes a package body for accommodating articles to be treated at a high pressure, and an irreversible pressure-sensitive marker disposed on the package body at a position capable of being seen from the exterior of the package body and adapted to develop color when pressurized.

FIELD OF ART

The present invention relates to a package to be used for treating foodsor the like under a specific high pressure condition. Particularly, thepresent invention is concerned with a package for high pressuretreatment capable of being easily determined whether it has beensubjected to a high pressure treatment or not, as well as a method fortreating foods at a high pressure.

BACKGROUND ART

Recently, in the field of packaged food, a technique applying a highpressure treatment of several hundred MPa to minimizing the heatdenaturation of food components for improving the added value of foodtypified by flavor and the like attracts attention as a technique insubstitution for the conventional sterilization by heating or as animproved treatment technique from the standpoint of the tendency toheighten the added value of food and the improvement of the shelf life.

The above high pressure treatment is sometimes used in combination withheat treatment. For example, in the case of a low acid food, it isnecessary to exterminate the spore-forming bacteria. However it hasbecome known that only the above high pressure treatment is notsufficient to exterminate the spore strain even at a pressure as high as600 MPa. Therefore, the high pressure treatment is used in combinationwith heat treatment.

The above high pressure treatment and heat treatment are performed withfoods accommodated in a container. For example, foods are contained in aflanged container composed of polypropylene resin or PET (polyethyleneterephthalate) resin having been subjected to deep drawing. Liquid suchas water is added to smooth the transfer of pressure in high pressuretreatment, and a film (top film) for closing an opening is applied to anupper surface of the container and is heat-sealed at a flanged edgeportion of the container.

The foods thus sealed within the container are placed into a highpressure apparatus which uses water or warm water as pressurizing mediumand are then treated at a predetermined pressure for a predeterminedtime. At this time, since the liquid is pressurized adiabatically,exothermic phenomenon occurs due to adiabatic compression. For example,applied pressures of 400 MPa and 800 MPa accompany temperature rises ofabout 6° C. and about 18° C. respectively, and the foods accommodated inthe container undergo an isotropic compression together with thecontainer. Upon pressure reduction after the pressurizing treatment, thetemperature returns to the original room temperature and the containerwhich has been contracted under compression also reverts to its originaldimensions.

However, if a large number of packaged foods are subjected to the highpressure treatment in such a form, there arises the problem that it ispractically impossible to make distinction between containers havingbeen subjected to the high pressure treatment and those not having beensubjected to the same treatment. As will be apparent from the abovedescription on the process, after the containers are subjected to a highpressure treatment using water or warm water, the containers often donot have any significant change in appearance. Thus, there remains noevidence of having gone through the high pressure treatment, making itvery difficult to make distinction from those before the treatment.

In case of performing a heat treatment subsequent to the high pressuretreatment and in case of treating products on a production line on whichthe products flow in one direction, it is possible to distinguishwhether a product has been subjected to the high pressure treatment ornot if the minute process control is performed. However, in a workingenvironment in which there are various kinds of products in a mixedstate, it is impossible to make the aforesaid distinction, which is aserious problem in the production.

Focusing on the above-mentioned problem, such a heat treatment checkingsystem in a heat treatment process for food as is described in PatentLiterature 1 is proposed heretofore. FIG. 5 is a perspective viewshowing a part of the heat treatment checking system and an outline of aretort food sterilizing process.

This heat treatment checking system 100 includes a mount (a productaccommodating basket) 30 for conveying a to-be-treated material (retortfood A) to an apparatus for performing heating or cooling treatment forfood, a detection sensor 10B provided in the mount 30 and capable ofstoring the history of treatment temperature, and a deformation checkingsensor 20. The detection sensor 10B is a shape memory alloy adapted tochange in shape depending on the heat treatment temperature and thedeformation checking sensor 20 detects a state of deformation of theshape memory alloy directly or indirectly.

However, because the detection sensor 10B capable of storing the historyof treatment temperature is provided for each mount 30 which conveys ato-be-treated material, the conventional heat treatment checking system100 does not determines whether each individual to-be-treated materialaccommodated in the mount 30 has been heat-treated or not. Thus, it isunfortunately impossible to track each individual to-be-treated materialtaken out from the mount 30 in the conventional system. Further, in theheat treatment checking system 100, the history of treatment temperaturecan be stored for each mount 30 for conveying the to-be-treatedmaterial, but it is impossible to store the history of pressurizingtreatment.

[Patent Literature 1] Japanese Patent Laid Open No. 2002-142736

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a package for highpressure treatment and a method for treating foods at a high pressure,both for solving the above-mentioned problems of the related art andbeing able to easily determine whether foods accommodated in the packagehave been subjected to a high pressure treatment or not.

For achieving the above-mentioned object, the package for high pressuretreatment according to the present invention comprises a package bodyfor accommodating articles to be subjected to a high pressure treatmentand an irreversible pressure-sensitive marker disposed on the packagebody at a position capable of being seen from the exterior of thepackage body and adapted to develop color upon being pressurized. Themethod for treating foods at a high pressure according to the presentinvention comprises accommodating foods within the package body of thepackage for high pressure treatment and subjecting the package for highpressure treatment to a high pressure treatment in the accommodatedstate of the foods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a high pressure treatment packagefor foods according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a sectional construction ofan irreversible pressure-sensitive marker according to the firstembodiment.

FIG. 3 is a schematic sectional view showing a sectional state in whichthe irreversible pressure-sensitive marker according to the firstembodiment is destroyed under a pressing force.

FIG. 4 is a perspective view showing an irreversible pressure-sensitivemarker according to a second embodiment of the present invention,corresponding to an enlarged perspective view of portion X in FIG. 1.

FIG. 5 is a perspective view showing a part of a conventional heattreatment checking system in a food heat-treating process and alsoshowing an outline of a retort food sterilizing process.

BEST MODE FOR CARRYING OUT THE INVENTION

First, a high pressure treatment package for foods according to a firstembodiment of the present invention will be described with reference toFIGS. 1 to 3. FIG. 1 is a perspective view showing a high pressuretreatment package for foods according to a first embodiment of thepresent invention, FIG. 2 is a schematic sectional view showing asectional construction of an irreversible pressure-sensitive markeraccording to the first embodiment, and FIG. 3 is a schematic sectionalview showing a sectional state in which the irreversiblepressure-sensitive marker according to the first embodiment is destroyedunder a pressing force.

The high pressure treatment package for foods according to this firstembodiment is for treating foods 10 shown in FIG. 1 at a high pressureand it includes a package body 7 which accommodates the foods 10 in theinterior thereof and an irreversible pressure-sensitive marker 1disposed on (for example, applied) the package body 7 at a positioncapable of being seen from the exterior of the package body 7 andadapted to develop color upon being pressurized. The package body 7includes a flanged container 8 and a top film 9. The flanged container 8is formed of a rigid plastic material, having a thickness of 100 to 300μm, with a flange portion 8 a being formed along edges of an opening.The top film 9 is composed of a soft resin, having a thickness of 50 to100 μm, and is bonded to the flange portion 8 a. The irreversiblepressure-sensitive marker 1 is applied on the top film 9 at a positioncapable of being seen from the exterior of the top film 9.

On the other hand, in the high pressure treatment for foods, isotropiccompression which utilizes the pressure of liquid is usually performedas noted above, therefore, an elastic material often tends to undergo areversible change such that it is deformed and contracted isotropicallywhen pressurized and reverts to its originals state when pressure isreduced. For example, in the case of a spherical shape, the originalshape tends to be restored without being destroyed.

Therefore, the marker as shown in FIG. 2 which has such capsules(microcapsules) 2 destroyed by pressure or load and with pigment 3sealed within each of the capsules, may be used as the irreversiblepressure-sensitive marker 1. When pressure or load is applied to themarker 1, the microcapsules 2 with the pigment 3 sealed therein aredestroyed and the interior pigment 3 oozes out and colors thesurrounding material.

However, even in the case of a microcapsule comprising a hollowspherical shell having a diameter of several ten to several hundredmicron meters, with a predetermined reagent or the like sealed withinthe shell, if the whole of the microcapsule undergoes isotropiccompression, the shell is often merely deformed elastically and notdestroyed until the pressure reaches a certain level. For destroying themicrocapsule surely at a predetermined pressure or higher, it isimportant that anisotropic pressure be applied thereto.

To meet this condition, the irreversible pressure-sensitive marker 1according to the first embodiment of the present invention includes abase member 4 having rigidity. The base member 4 has an installationsurface, and microcapsules 2 are disposed dispersedly on theinstallation surface. Also, a transparent film 5 composed of a softmaterial is formed on the installation surface so as to cover themicrocapsules 2. The transparent film 5 comprises a transparent adhesivewhich is applied after the dispersive arrangement of the microcapsules 2on the base member 4, or a thin, transparent film which is applied afterthe dispersive arrangement.

“Having rigidity” means that the base member possesses rigidity highenough to retain its shape against the pressure used in the highpressure treatment for the high pressure treatment package. “Havingrigidity” has the same meaning in the following description.

When the high pressure treatment package with the irreversiblepressure-sensitive marker 1 disposed thereon is subjected to the highpressure treatment, as shown in FIG. 3, anisotropic pressure, i.e., avertical pressing force 6, is exerted through the transparent film 5 onthe microcapsules 2 arranged on the installation surface 4 a of the basemember 4 having rigidity, thus making it possible to destroy thespherical microcapsules 2. Cracks 2 a are developed in the microcapsules2 as a result of the destruction and the pigment 3 oozes out from thecracks 2 a, presenting a color capable of being recognized visuallythrough the transparent film 5.

As the pigment 3 contained in the microcapsules 2, one which developscolor by reaction with another substance (a color former) may be used.In this case, two types of microcapsules 2, that is, microcapsules 2which contain pigment and microcapsules which contain a color former,may be used. As a simple example, a combination of a dilute iodinesolution and starch is taken.

The irreversible pressure-sensitive maker 1 according to the presentinvention does not always require the dedicated base member 4. Forexample, in a package printing process for the package body 7, a printmaterial with the pigment-sealed microcapsules 2 added thereto may beprinted to a portion of the package body 7 which can be seen from theexterior, thereby the irreversible pressure-sensitive marker 1 can beformed. The print material in this case preferably has a color capableof being distinguished from the color of the pigment which oozes out asa result of destruction of the microcapsules 2, or transparency.

In the case where the package body 7 is constituted by the flangedcontainer 8 composed of a rigid resin material, namely, a resin materialhaving rigidity, as shown in FIG. 1, if the irreversiblepressure-sensitive marker 1 is disposed on the flange portion 8 a, theflange portion 8 a plays the role of the base member having rigidity,therefore, the irreversible pressure-sensitive marker 1 itself is notalways required to include the base member 4 composed of a materialhaving rigidity.

However, in the case where the package body 7 is a mere bag composed ofa soft resin material, the irreversible pressure-sensitive marker 1preferably includes the base member 4 composed of a rigid resin in orderto exert an anisotropic pressing force on the microcapsules 2.

Next, with reference to FIG. 4, a description will be given about a highpressure treatment package for foods according to a second embodiment ofthe present invention. FIG. 4 is a partial detailed perspective viewshowing a principal portion of a package for high pressure treatmentaccording to a second embodiment of the present invention, correspondingto an enlarged view of portion X shown in FIG. 1. This second embodimentis different from the previous first embodiment in that the secondembodiment has an irreversible temperature-sensitive marker 11 inaddition to the irreversible pressure-sensitive marker 1. Otherconstructional points are just the same as in the first embodiment.Therefore, the same portions as in the first embodiment are denoted bythe same references numerals and the difference will be described below.

In the high pressure treatment package for foods according to theprevious first embodiment, the irreversible pressure-sensitive marker 1adapted to develop color when pressurized is disposed on the packagebody 7 at a position capable of being seen from the exterior of thepackage body 7. On the other hand, the high pressure treatment packagefor foods according to this second embodiment is provided with anirreversible temperature-sensitive marker 11 which develops color at aheat treatment temperature, in addition to the irreversiblepressure-sensitive marker 1. As the irreversible temperature-sensitivemarker 11, a commercially available thermo-label whose color developmentlevel changes depending on the heat treatment temperature may be used.

According to this package for high pressure treatment, in the case wherethe foods accommodated in the package body 7 are to be subjected to bothhigh pressure treatment and heat treatment, it is possible to easilydetermine whether the foods go through both the treatments or not from achange in color of the two markers 1 and 11.

As described above, since the package for high pressure treatmentaccording to the present invention includes a package body foraccommodating articles to be subjected to the high pressure treatment,and an irreversible pressure-sensitive marker disposed on the packagebody at a position capable of being seen from the exterior of thepackage and adapted to develop color when pressurized, it is possible torecognize obviously whether each individual package for high pressuretreatment is subjected to the high pressure treatment or not.

The articles to be accommodated in the package for high pressuretreatment according to the present invention are not limited to foods.The package is also applicable to, for example, water-containing liquidmedical drugs (e.g., instillation) to which heat sterilization orradioactive sterilization is not applicable. It is further applicable toresinous bags for containing chemicals, as well as medical instruments.However, the present invention is effective particularly for highpressure treatment for foods. Recently, the high pressure treatment forfoods which improve the shelf life attracts attention, and it is thoughtthat the high pressure treatment will become more and more popular infuture. With the high pressure treatment package for foods according tothe present invention, it becomes easier to determine whether the foodsare subjected to the high pressure treatment or not in process controlduring manufacture of high pressure-treated foods, or it becomes easierfor a seller or a consumer to determine whether the commodity concernedis subjected to the high pressure treatment as indicated thereon at aretail store. Thus, from the standpoint of not only process control butalso ensuring the safety of food, the package of the present inventionmakes a great contribution to the development of the food industry andthe soundness of the society.

As the irreversible pressure-sensitive marker, it is preferable to use,for example, a marker comprising a base member having an installationsurface, microcapsules disposed dispersedly on the installation surfaceof the base member and with pigment sealed therein, and a transparentfilm formed on the installation surface, the microcapsules having afunction of being destroyed and developing color upon being pressurized,or a marker comprising a base member, and a print material formed on thebase member by printing and containing microcapsules with pigment sealedtherein, the microcapsules having a function of being destroyed anddeveloping color upon being pressurized.

Since anisotropic pressure acts on the microcapsules of the irreversiblepressure-sensitive marker from the side opposite to the installationsurface, the microcapsules are more likely to be destroyed in comparisonwith the case where isotropic pressure acts on the microcapsules. Thepigment oozing out from the destroyed microcapsules colors anappropriate portion to exhibit distinction.

The package body preferably includes a flanged container having a flangeportion, and a top film bonded to the flange portion to maintain thearticles accommodated within the flanged container in a sealedcondition. With respect to the package body, the irreversiblepressure-sensitive marker may be disposed on an outer surface of theflanged container or at a bonded portion of the top film.

If the package body includes a portion composed of a rigid material andhaving an installation surface, and the irreversible pressure-sensitivemarker includes microcapsules disposed dispersedly on the installationsurface of the package body and with pigment sealed therein and furtherincludes a transparent film formed on the installation surface, and themicrocapsules has a function of being destroyed and developing colorupon being pressurized, then the irreversible pressure-sensitive markerno longer requires a dedicated base member because the package bodyplays the role of the base member.

The package body may include a portion composed of a rigid material andhaving an installation surface, the irreversible pressure-sensitivemarker may comprise a print material formed on the installation surfaceof the package body by printing and containing microcapsules withpigment sealed therein, and the microcapsules may have a function ofbeing destroyed and developing color upon being pressurized.

More specifically, it is preferable that the package body includes aflanged container having a flange portion and also includes a top filmbonded to the flange portion to maintain the articles accommodatedwithin the flanged container in a sealed condition, and the flangeportion is composed of a rigid material and has the installationsurface.

It is more preferable that the package for high pressure treatment ofthe present invention further comprises an irreversibletemperature-sensitive marker provided on the package body and adapted todevelop color at a heat treatment temperature. In the case where thearticles accommodated within the package body are to be subjected toboth high pressure treatment and heat treatment, the irreversibletemperature-sensitive marker makes it possible to recognize whether boththe treatments are completed for the articles or not.

The present invention also provides a method for treating foods at ahigh pressure, comprising: accommodating foods within the package bodyof the package for high pressure treatment, and subjecting the packagefor high pressure treatment to a high pressure treatment in theaccommodated state of the foods.

According to this method, it is possible to easily recognize, after thehigh pressure treatment, whether the package is actually subjected tothe high pressure treatment or not.

Further, in a method according to the present invention, comprisingaccommodating foods within the package body of the package for highpressure treatment, the package body being provided with theirreversible temperature-sensitive marker, and subjecting the packagefor high pressure treatment to both high pressure treatment and heattreatment in the accommodated state of the foods, it is also possible toeasily recognize whether the package is actually subjected to heattreatment or not in addition to the high pressure treatment.

1. A package for high pressure treatment, the package accommodatingarticles in the interior thereof for subjecting the articles to a highpressure treatment, the package comprising: a package body accommodatingthe articles; and an irreversible pressure-sensitive marker disposed onsaid package body at a position capable of being seen from the exteriorof said package body and adapted to develop color upon beingpressurized.
 2. The package for high pressure treatment according toclaim 1, wherein said irreversible pressure-sensitive marker includes abase member having an installation surface, microcapsules disposeddispersedly on said installation surface of said base member and withpigment sealed therein, and a transparent film formed on saidinstallation surface, said microcapsules having a function of beingdestroyed and developing color upon being pressurized.
 3. The packagefor high pressure treatment according to claim 1, wherein saidirreversible pressure-sensitive marker includes a base member, and aprint material formed on said base member by printing and containingmicrocapsules with pigment sealed therein, said microcapsules having afunction of being destroyed and developing color upon being pressurized.4. The package for high pressure treatment according to claim 1, whereinsaid package body includes a flanged container having a flange portion,and a top film bonded to said flange portion to maintain the articlesaccommodated within said flanged container in a sealed condition, andsaid irreversible pressure-sensitive marker is disposed on an outersurface of said flanged container or at a bonded portion of said topfilm.
 5. The package for high pressure treatment according to claim 1,wherein said package body includes a portion composed of a rigidmaterial and having an installation surface, and said irreversiblepressure-sensitive marker includes microcapsules disposed dispersedly onsaid installation surface of said package body and with pigment sealedtherein and also includes a transparent film formed on said installationsurface, said microcapsules having a function of being destroyed anddeveloping color upon being pressurized.
 6. The package for highpressure treatment according to claim 1, wherein said package bodyincludes a portion composed of a rigid material and having aninstallation surface, and said irreversible pressure-sensitive markercomprises a print material formed on said installation surface of saidpackage body by printing and containing microcapsules with pigmentsealed therein, said microcapsules having a function of being destroyedand developing color upon being pressurized.
 7. The package for highpressure treatment according to claim 5, wherein said package bodyincludes a flanged container having a flange portion and also includes atop film bonded to said flange portion to maintain the articlesaccommodated within said flanged container in a sealed state, saidflange portion being composed of a rigid material and having saidinstallation surface.
 8. The package for high pressure treatmentaccording to claim 1, further comprising an irreversibletemperature-sensitive marker provided on said package body and adaptedto develop color at a heat treatment temperature.
 9. The package forhigh pressure treatment according to claim 1, wherein said package bodyaccommodates foods.
 10. A method for treating foods at a high pressure,comprising: accommodating foods within said package body of the packagefor high pressure treatment described in claim 1; and subjecting thepackage for high pressure treatment to a high pressure treatment in theaccommodated state of the foods.
 11. A method for treating foods at ahigh pressure, comprising: accommodating foods within said package bodyof the package for high pressure treatment described in claim 8; andsubjecting the package for high pressure treatment to both high pressuretreatment and heat treatment in the accommodated state of the foods. 12.The package for high pressure treatment according to claim 6, whereinsaid package body includes a flanged container having a flange portionand also includes a top film bonded to said flange portion to maintainthe articles accommodated within said flanged container in a sealedstate, said flange portion being composed of a rigid material and havingsaid installation surface.